Circuit Description
The TAP Shift system allows the driver to manually shift gears by using the TAP Shift switches located on the automatic transmission shifter. Pushing the Up switch will command an upshift and pushing the Down switch will command a downshift. The TAP Shift system is activated when the gear selector is in the manual, M, position and is deactivated in all other positions.
If the TCM detects TAP enable switch Active and the IMS does not indicate D5, DTC P1876 sets. DTC P1876 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1876 Up and Down Shift Switch Performance - Range Switch Not in D3
Conditions for Running the DTC
| • | No TAP system DTCs P0815, P0816 or P0826. |
| • | No IMS range DTCs P1815, P1820, P1822, P1823, P1825 or P1826. |
| • | The engine run time is greater than 5 seconds. |
| • | No CAN errors present. |
Conditions for Setting the DTC
The TCM detects the TAP enable switch is Active and the IMS range is not D for 5 seconds.
Action Taken When the DTC Sets
| • | The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM disables TAP Shift operation. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information a Failure Record. |
| • | The TCM stores DTC P1876 in TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear DTC Information function erases the Failure Records from the PCM. Does the scan tool Driver Shift Request parameter display None? | -- | Go to Intermittent Conditions in Engine Controls -4.6L | Go to Step 3 | ||||||
3 | Select Driver Shift Request Voltage on the scan tool. Does the Driver Shift Request Voltage parameter display a value higher than specified? | 0.5 V | Go to Step 4 | Go to Step 5 | ||||||
4 | Does the Driver Shift Request Voltage parameter display a value lower than specified? | 4.5 V | Go to Step 9 | Go to Step 8 | ||||||
5 |
Refer to Circuit Protection - Fuses in Wiring Systems. Was the fuse open? | -- | Go to Step 6 | Go to Step 7 | ||||||
6 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Intermittent Conditions in Engine Controls - 4.6L | ||||||
7 | Test the ignition 1 voltage circuit of the A/T Shift Program Switch for an open between the fuse block and the A/T Shift Program Switch. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||
8 | Test the signal circuit of the A/T Shift Program Switch for an open or short to ground between the A/T Shift Program Switch and the PCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||
9 |
Is the resistance within the specified range? | 8.11-8.39K ohms | Go to Step 10 | Go to Step 11 | ||||||
10 | Replace the A/T Shift Program Switch. Refer to Parking System Components Removal in Automatic Transmission 5L40/5L50 - Unit Repair. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
11 | Replace the TCM. Refer to Control Module References in Computer/Integrating Systems for replacement, set-up and programming. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 13 | Go to Step 2 | ||||||
13 | With a scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
